Heating device.



J. R. & E. D. HOLLEY.

- HEATING DEYIOE. APPLICATION FILED SEPT. a, 1908.

926, 1 88, Patented June 29, 1909.

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UNITED STATES PATENT QFFIOE.

I JULIAN It. HOLLEY, OF bRISTOL, AND EVERETT D. HOLLEY, OF FORESTVILLE,

CONN EGTIGUT.

HEATING- DEVICE.

Specification of Letters Patent.

Patented June 29, 1909.

Application filed September 3, 1908. Serial No. 451,944.

To all whom it may concern:

Be it known that we, JULIAN R. HOLLEY and EVERETT D. HOLLEY, citizens of the United States, and residents of Bristol and.

Forestville, respectively, in the county of Hartford and State of Connecticut, have invented certain new and useful Improvements in Heating Devices, of which thefollowing is a full, clear, and exact specifica-- ily connected into acircuit, and in which the liability to damage from overheating -is practically obviated;

Our invention has, furthermore, for its object the provision of a flat-face until the entire heating surface of which is heated in a substantially uniform degree, so that the diffusion of the heat will be equalon all parts thereof.

Our invention has, furthermore, for its object the improved manner ofattaching the unit to a vessel to be heated. I

Briefly stated, our invention comprises an electrical heat-unit having a flat contact surface with the article to be heated, this flat surface being formed by a thin layer of mica which insulates or protects the heatiinparting medium or wire from short-circuit. This wire is in the present instance in the form of a ribbon which is laid fiatwise on a body of insulating material and the several runs or adjacent layers of which are substantially disposed in parallelism soas to provide a clearance space of suflicient width to'preveut arcing.

In the accompanying drawings, in which similar characters denote similar parts. Figure 1 isa vertical section of a unit embodying our invention applied to the bottom plate of a vessel or dish, and Fig. 2 represents a horizontal section on line 2, 2 of Fig. 1.

In the drawings, 10 denotes the bottom of a vessel or pot which has Securedthereto a heat-concentrating base plate 11 with which our improved heat-unit is adapted to come into direct contact. The unit comprises, in its preferred form, a disk 12, made of insulating material such as for instance soap stone, the upper face of which contains the heating medium which consists of a flat ribbon wire 13 ofconducting material in such proportions as to offer a substantial resistance to the passage of the current. The wire ribbon 13 may be formed either by winding the same edgewise into spiral form, as shown 'in Fig. 2 or the entire resistance member may be produced by punch-and-die process so as to have the several adjacent runs-or convolution's in parallelism and separated by airspaces to prevent short-circuit and the consequent loss of resistance and heat. The disk 12 has apertures 15, 16, through which the ends of the resistance wire pass to a point below said disk which may be comparatively thin and then reinforcedby a plate 20 also preferably made of soap stone and having T1138 21 for supporting the central portions of the disk 12 which may be otherwise separated therefrom by air-spaces 22 to avoid the radiation of heat. The resistance ribbon 13 is covered by a thin layer of mica 25 which serves as an insulator to guard the ribbon against contact with the metal base plate 11, while at the same time its thickness will not preclude a rapid and thorough heat pimetration to the lower surface of said base p ate.

In order to render the unit self-contained,

we prefer to employ the consolidation of the several parts asshown in Figfl, in which the soap stone-base20, the resistancecarrying disk 12, and mica insulator 25 are represented assembled within a' cup-shaped shell 26 and drawn together therewith by screw-threaded bolts 27 having flanged heads 28 and nuts 29.

Passing through the tubular bolts 27 are screws 30 which are threaded in the base plate 11 and serve to bring the entire unit and more especially its upper surface into contact with the bottom of the base plate 11.

Many changes may be made in the formation of the resistance ribbon, which in the present instance is formed in the shape of a spiral, substantially the same results being obtained when the ribbon is formed zig-zag or in serpentine form.

The terminals for connecting the unit to the main wires of a power-current, may be of any desired construction, the drawing representing only the ends or the resistance ribbon as they protrude from the insulator. casing.

We claim: l. A heat-unit comprising a resistanceribbon wound flatwise into a series of successive convolutions which are separated from each other by substantially-uniform air spaces, whereby the diffusion of heat from said resistance ribbon will be substantially uniform over the entire surface thereof.

2. A heat-unit consisting. of an insulating body, a resistance-ribbon resting-i fiatwise thereon and Wound flatwise to form a' series of continuous spiral convolutions separated from each other by substantially-uniform air spaces to prevent short circuit, and a cover of electric insulating and heat conducting material over said resistance ribbon.

JULIAN R. HOLLEY.

EVERETT D. HOLLEY. Witnesses:

HARRY i LAW, C. F. SoHMnLz. 

